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  • 1
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    The Lithospheric Structure of the Saharan Metacraton From 3‐D Integrated Geophysical‐Petrological Modeling (2021)
    Wiley Agu
    Details
    Publikationsdatum: 2021-04-07
    Beschreibung: We modeled crustal and lithospheric thickness variation as well as the variations in temperature, composition, S wave seismic velocity, and density of the lithosphere beneath the Saharan Metacraton (SMC) applying an interdisciplinary 3‐D modeling. Regardless of the limited data set, we aimed at consistent imaging of the SMC lithospheric structure by combining independent data sets to better understand the evolution of the metacraton. We considered that the SMC was once an intact Archean‐Paleoproterozoic craton but was metacratonized during the Neoproterozoic due to partial loss of its subcontinental lithospheric mantle (SCLM) during collisional processes along its margin. This has permitted the preservation of three cratonic remnants (Murzuq, Al‐Kufrah, and Chad) within the metacraton. These cratonic remnants are overlain by Paleozoic‐Mesozoic sedimentary basins (Murzuq, Al‐ Kufrah, and Chad), which are separated by topographic swells associated with the Hoggar Swell, Tibesti Massif, and Darfur Dome Cenozoic volcanism. The three cratonic remnants are underlain by a relatively thicker lithosphere compared to the surrounding SMC, with the thickest located beneath Al‐Kufrah reaching 200 km. Also, the SCLM beneath Al‐Kufrah cratonic remnant is significantly colder and denser. Modeling of the lithosphere beneath the Chad and Murzuq Basins yielded a complex density and temperature distribution pattern, with lower values than beneath the Tibesti Massif. Further, our modeling indicated a uniform and moderately depleted mantle composition beneath the SMC. The presence of a relatively thinner lithosphere beneath the noncratonic regions of the SMC is attributed with several tectonic events, including partial SCLM delamination during the Neoproterozoic, Mesozoic‐Cenozoic rifting, and Cenozoic volcanism.
    Beschreibung: Published
    Beschreibung: e2019JB018747
    Beschreibung: 1T. Struttura della Terra
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 2
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    Performance Enhancement and Capacity Enlargement for a DWDM-PON System Utilizing an Optimized Cross Seeding Rayleigh Backscattering Design (2020)
    Details
    Publikationsdatum: 2020-03-20
    Beschreibung: In this work, a record of 16 channels, with future channel spacing in the telecommunication standardization sector of the International Telecommunications Union G.694.1 (ITU-T G.694.1) for Dense Wavelength Division Multiplexing (DWDM) (i.e., 12.5 GHz), is simulated and tested. This work is done to realize a proposed high capacity DWDM-Passive Optical Network (DWDM-PON) system. These specifications are associated with enhancing the upstream (US) capacity to 2.5 Gb/s over a 25 km Single-Mode Fiber (SMF) transmission and producing a noteworthy average Bit Error Rate (BER) of 10−12 during the system’s evaluation process. These performance indicators are achieved through design optimization of the cross-seeding Rayleigh Backscattering (RB) elimination technique. This optimization has successfully reduced (compared to the cross-seeding related literature) the simulated DWDM-PON components and maintained an effective Rayleigh Backscattering elimination with the aforementioned system’s performance enhancement and capacity enlargement.
    Beschreibung: Published
    Beschreibung: id 4520
    Beschreibung: 2TR. Ricostruzione e modellazione della struttura crostale
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 3
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    Moho Depth and Crustal Architecture Beneath the Levant Basin from Global Gravity Field Model (2019)
    Details
    Publikationsdatum: 2019-03-28
    Beschreibung: The study of the discontinuity between the Earth crust and upper mantle, the so-called Moho, and of the lithospheric architecture in general, has several important applications in exploration geophysics. For instance, it is used to facilitate the inversion of seismic-related data, in order to obtain important information on the sedimentary layers or to study the Earth’s heat flux. In this paper, the Levant crustal structure is being investigated starting from the inversion of gravity disturbances coming from a global geopotential field model based on ESA GOCE satellite mission integrated with seismic derived information. In the considered area, which is of particular interest because of its richness from the resources point of view, the deep crustal structure is still a matter of study due to the presence of a thick sequence of sedimentary layers, deposited within geological eras by the Nile River. Within the current work, the shape of the Oceanic domain in correspondence to the Herodotus Basin and the Cyprus Arc has been clearly defined. Moreover the nature of the Levantine Basin and of the Eratosthenes crust has been investigated by a set of ad hoc tests, finding the presence of continental crust. Finally, the Moho depth and the crustal density distribution have been retrieved. Several localized anomalies, in the Cyprus area, have been identified and modelled too, thus confirming the presence of heavy material, with a thickness up to 10 km, in the sedimentary layer and shallower part of the crust.
    Beschreibung: Published
    Beschreibung: id 200
    Beschreibung: 2TR. Ricostruzione e modellazione della struttura crostale
    Beschreibung: JCR Journal
    Schlagwort(e): gravity inversion; ; Levant crustal structure; ; Moho
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 4
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    Validation of recently released GOCE-based satellite-only global geopotential models over the Red Sea using shipborne gravity data (2019)
    Details
    Publikationsdatum: 2019-04-01
    Beschreibung: The gravity fi eld and steady-state ocean circulation explorer (GOCE) satellite, successfully concluded its mission in October 2013 after collecting unprecedented gravity gradient measurements. Such GOCE data made it possible to improve the determination of the geoid over the Red Sea region. The performance of GOCE-based satellite-only global geopotential models (GGMs), at the end of its mission, is evaluated via spectral analysis and by using shipborne free-air gravity anomalies collected over the study area, namely the Red Sea. Eight of the most recent GOCE-based satelliteonly GGMs, namely the DIR_R5, ITU_GGC16_2, SPW_R5, TIM_R5, NULP_02S, IfE_GOCE05s, IGGT_R1, and GGM05G, are validated. Firstly, the spectral analysis of these GGMs was performed. The DIR_R5 model showed a superior behaviour, in all terms, in comparison to all the investigated GGMs. Then, the GGMs were evaluated, from spherical harmonics degree/order (d/o) ranging from 100 to their maximum d/o, with respect to the shipborne gravity data after applying the spectral enhancement method, to overcome the existing spectral gap. All the studied GGMs closely calculated the full power of gravity anomaly at a spherical harmonic d/o equivalent to 160. Regardless of the cross-comparable results obtained by the DIR_R5, TIM_R5, SPW_ R5, ITU_GGC16_2, and IfE_GOCE05s, whose standard deviation (STD) values of the differences with respect to shipborne data range from 9.90 and 9.93 mGal, the SPW_ R5 model produced the best results with discrepancies characterised with a minimum, maximum, mean, and STD of -56.26, 131.29, 2.07, and 9.90 mGal, respectively.
    Beschreibung: Published
    Beschreibung: 267-284
    Beschreibung: 2TR. Ricostruzione e modellazione della struttura crostale
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 5
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    A New Tool for Airborne Gravimetry Survey Simulation (2019)
    Details
    Publikationsdatum: 2019-03-27
    Beschreibung: Airborne gravimetry represents nowadays probably the most efficient technique to collect gravity observations close to the Earth’s surface. In the 1990s, thanks to the development of the Global Navigation Satellite Systems (GNSS), which has made accurate navigational data available, this technique started to spread worldwide because of its capability to provide measurements in a fast and cost-effective way. Differently from other techniques such as shipborne gravimetry, it has the advantage to provide gravity measurements also in challenging environments which can be difficult to access otherwise, like mountainous areas, rain forests and polar regions. For such reasons, airborne gravimetry is used for various applications related to the regional gravity field modelling: from the computation of high accurate local geoid for geodetic applications to geophysical ones, specifically related to oil and gas exploration activities or more in general for regional geological studies. Depending on the different kinds of application and the final required accuracy, the definition of the main characteristics of the airborne survey, e.g., the planar distance between consecutive flight tracks, the aircraft velocity, etc., can be a difficult task. In this work, we present a new software package, which would help in properly accomplishing the survey design task. Basically, the developed software solution allows for generating a realistic (from the observation noise point of view) gravimetric signal, and, after that, to predict the accuracy and spatial resolution of the final retrievable gravimetric field, in terms of gravity disturbances, given the flight main characteristics. The proposed procedure is suited for airborne survey planning in order to be able to optimize the design of the survey according to the required final accuracy. With the aim to evaluate the influence of the various survey parameters on the expected accuracy of the airborne survey, different numerical tests have been performed on simulated and real datasets. For instance, it has been shown that if the observation noise is not properly modeled in the data filtering step, the survey results degrade about 25%, while not acquiring control lines during the survey will basically reduce the final accuracy by a factor of two.
    Beschreibung: Published
    Beschreibung: id 292
    Beschreibung: 2TR. Ricostruzione e modellazione della struttura crostale
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 6
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    Regional Gravity Field Model of Egypt Based on Satellite and Terrestrial Data (2020)
    Details
    Publikationsdatum: 2020-03-20
    Beschreibung: This study presents a recent combined regional gravity field model over Egypt, developed by integrating satellite and terrestrial data via applying the remove-compute-restore (RCR) principle and the least-squares collocation (LSC) procedure. A high-resolution digital terrain model was exploited for the computation of the terrain and residual terrain corrections. Hereby, all the signals that can be modelled or deterministically computed are considered known and then removed in order to reduce the order of magnitude of the input gravity data prior to applying the LSC. Several GOCE-only and combined global geopotential models (GGMs) have been thoroughly investigated with respect to the EGM2008, in which the space-wise (SPW) solution, namely the SPW-R5 model, demonstrated the best performance. For the development of the combined model, the SPW-R5 GGM has been integrated with both the EGM2008 GGM and the terrestrial data retrieved from 56,250 gravity stations of the Getech data, acquired in the framework of the African Gravity Project. The combined regional gravity model was compared to the state-of-art XGM2016 global gravity model. The standard deviation of the differences is 18.0 mGal in terms of Bouguer anomalies. The combined regional model fits well with the terrestrial gravity data along the chosen North–South oriented profile through the Nile Delta region. The improvements of the developed combined regional model over the XGM2016 are due to the use of a more extensive terrestrial dataset. In conclusion, our model is more suitable than solely using the ground data or GGMs for regional density modelling over Egypt. As an example, the comparison of using a global or regionally defined gravity model with the forward gravity modelling based on Saleh (Acta Geodaetica et Geophysica Hungarica 47(4):402–429, 2012) density model is performed.
    Beschreibung: Published
    Beschreibung: 767–786
    Beschreibung: 2TR. Ricostruzione e modellazione della struttura crostale
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 7
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    Inverse and 3D forward gravity modelling for the estimation of the crustal thickness of Egypt (2020)
    Elsevier
    Details
    Publikationsdatum: 2022-06-09
    Beschreibung: A 3D crustal density model for Egypt was compiled. It is constrained by available deep seismic refraction, receiver functions analysis, borehole, and geological data. In Egypt, seismic data are sparsely and irregularly distributed. Consequently, we developed the crustal thickness model by integrating seismic and gravity data. Satellite gravity data was inverted to build an initial model, which was followed by a detailed 3D forward gravity modelling. The initial crustal thickness is determined by applying seismically constrained non-linear inversion, based on the modified Bott's method and Tikhonov regularization assuming spherical Earth approximation. Moreover, the gravity inversion-based Moho depth estimates are in good agreement with results of seismic studies and are exploited for the 3D forward modelling. Crustal thicknesses range from 25 to 30 km along the rifted margins of the Red Sea, which thin toward the Mediterranean Sea. Thicknesses in southern Egypt reach values between 35 and 40 km. A maximum crustal thickness of 45 km is found in the southwestern part of Egypt. Within the Sinai Peninsula, the thickness varies from the shallow southern edge (∼ 31 km) and increases toward the North (∼ 36 km). Our model revealed a thick lower crust beneath the southern part of Egypt, which can be associated with crustal modification that occurred during the collision of East Gondwana and the Saharan Metacraton along the Keraf suture zone during the final assembly of Gondwana in the Neoproterozoic. Finally, the isostatic implications of the differences between the seismic and gravity-derived Mohos are thoroughly discussed. In conclusion, the developed 3D crustal thickness model provides high-resolution Moho depth estimates that closely resembles the major geological and tectonic features. Also, the existing correlation between the topography, Bouguer anomalies, and Moho depths indicates that the investigated area is close to its isostatic equilibrium.
    Beschreibung: Published
    Beschreibung: 52-67
    Beschreibung: 2TR. Ricostruzione e modellazione della struttura crostale
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 8
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    Comparison of Satellite Altimetric Gravity and Global Geopotential Models with Shipborne Gravity in the Red Sea (2018)
    Taylor & Francis
    Details
    Publikationsdatum: 2018-02-21
    Print ISSN: 0149-0419
    Digitale ISSN: 1521-060X
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geologie und Paläontologie , Physik
    Publiziert von Taylor & Francis
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  • 9
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    Inverse and 3D forward gravity modelling for the estimation of the crustal thickness of Egypt (2019)
    Elsevier
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: A 3D crustal density model for Egypt was compiled. It is constrained by available deep seismic refraction, receiver functions analysis, borehole, and geological data.In Egypt, seismic data are sparsely and irregularly distributed. Consequently, we developed the crustal thickness model by integrating seismic and gravity data. Satellite gravity data was inverted to build an initial model, which was followed by a detailed 3D forward gravity modelling. The initial crustal thickness is determined by applying seismically constrained non-linear inversion, based on the modified Bott's method and Tikhonov regularization assuming spherical Earth approximation. Moreover, the gravity inversion-based Moho depth estimates are in good agreement with results of seismic studies and are exploited for the 3D forward modelling.Crustal thicknesses range from 25 to 30 km along the rifted margins of the Red Sea, which thin toward the Mediterranean Sea. Thicknesses in southern Egypt reach values between 35 and 40 km. A maximum crustal thickness of 45 km is found in the southwestern part of Egypt. Within the Sinai Peninsula, the thickness varies from the shallow southern edge (∼ 31 km) and increases toward the North (∼ 36 km). Our model revealed a thick lower crust beneath the southern part of Egypt, which can be associated with crustal modification that occurred during the collision of East Gondwana and the Saharan Metacraton along the Keraf suture zone during the final assembly of Gondwana in the Neoproterozoic. Finally, the isostatic implications of the differences between the seismic and gravity-derived Mohos are thoroughly discussed.In conclusion, the developed 3D crustal thickness model provides high-resolution Moho depth estimates that closely resembles the major geological and tectonic features. Also, the existing correlation between the topography, Bouguer anomalies, and Moho depths indicates that the investigated area is close to its isostatic equilibrium.
    Print ISSN: 0040-1951
    Digitale ISSN: 1879-3266
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Elsevier
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  • 10
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    Regional Gravity Field Model of Egypt Based on Satellite and Terrestrial Data (2018)
    Springer
    Details
    Publikationsdatum: 2018-09-03
    Print ISSN: 0033-4553
    Digitale ISSN: 1420-9136
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Springer
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